Ethanolamine, which is also known by the name monoethanolamine, which in turn can be abbreviated as MEA, is a special organic chemical compound that is defined as a primary alcohol and amine compound, due to its involvement with the hydroxyl group. Much like other amines, this compound acts as a weaker base. The compound itself is highly toxic, flammable, and corrosive, and should always be handled with care. It is commonly seen as a colorless, viscous liquid that has an aroma that is similar to that of ammonia. This compound is the second most abundant group of phospholipids, which are substances that are typically found in biological membranes. It is commonly used as a messenger molecule, especially in the case of palmitoylethanolamide, where it has a visible effect on CB1 receptors. There is also a specialized class of antihistamines that is identified under this name, and it includes common compounds such as clemastine, diphenhydramine, and doxylamine.